Chapter 51 Behavioral Ecology.

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2 Overview: Studying BehaviorHumans have probably studied animal behavior for as long as we have lived on EarthAs hunters, knowledge of animal behavior was essential to human survival

3 Cranes are birds that have captivated people’s interest, possibly because they are large and their behavior is easily observedVideo: Albatross Courtship RitualVideo: Blue-footed Boobies Courtship RitualVideo: Giraffe Courtship Ritual

5 Behavioral ecology extends observations of animal behavior by studying how such behavior is controlled and how it develops, evolves, and contributes to survival and reproductive success

6 Concept 51.1: Behavioral ecologists distinguish between proximate and ultimate causes of behaviorScientific questions about behavior can be divided into two classes:Those that focus on the immediate stimulus and mechanism for the behaviorThose that explore how the behavior contributes to survival and reproduction

7 What Is Behavior? Behavior is what an animal does and how it does itBehavior includes muscular and nonmuscular activity

10 Proximate and Ultimate QuestionsProximate, or “how,” questions focus on:Environmental stimuli that trigger a behaviorGenetic, physiological, and anatomical mechanisms underlying a behaviorUltimate, or “why,” questions focus on evolutionary significance of a behavior

11 EthologyEthology is the scientific study of animal behavior, particularly in natural environments

12 Ethologists developed a conceptual framework defined by a set of questionsThese questions highlight the complementary nature of proximate and ultimate perspectives

13 Fixed Action PatternsA fixed action pattern (FAP) is a sequence of unlearned, innate behaviors that is unchangeableOnce initiated, it is usually carried to completionA FAP is triggered by an external sensory stimulus known as a sign stimulus

14 In male stickleback fish, the stimulus for attack behavior is the red underside of an intruder

16 When presented with unrealistic models, as long as some red is present, the attack behavior occurs

17 LE 51-4BEHAVIOR: A male stickleback fish attacks other male sticklebacks that invade its nesting territory.PROXIMATE CAUSE: The red belly of the intruding male acts as a sign stimulus that releases aggression in a male stickleback.ULTIMATE CAUSE: By chasing away other male sticklebacks, a male decreases the chance that eggs laid in his nesting territory will be fertilized by another male.

18 ImprintingImprinting is a behavior that includes learning and innate components and is generally irreversibleIt is distinguished from other learning by a sensitive periodA sensitive period is a limited developmental phase that is the only time when certain behaviors can be learned

19 An example of imprinting is young geese following their mother Konrad Lorenz showed that when baby geese spent the first few hours of their life with him, they imprinted on him as their parentThere are proximate and ultimate causes of this type of behaviorVideo: Ducklings

20 BEHAVIOR: Young geese follow and imprint on their mother.LE 51-5BEHAVIOR: Young geese follow and imprint on their mother.PROXIMATE CAUSE: During an early, critical developmental stage, the young geese observe their mother moving away from them and calling.ULTIMATE CAUSE: On average, geese that follow and imprint on their mother receive more care and learn necessary skills, and thus have a greater chance of surviving than those that do not follow their mother.

21 Conservation biologists have taken advantage of imprinting in programs to save the whooping crane from extinction

23 Concept 51.2: Many behaviors have a strong genetic componentBiologists study how genes and environment influence development of behavioral phenotypesInnate behavior is developmentally fixed and under strong genetic influence

25 KinesisA kinesis is a simple change in activity or turning rate in response to a stimulusFor example, sow bugs become more active in dry areas and less active in humid areas

26 Kinesis increases the chance that a sow bug will encounter and stay LE 51-7aMoist siteunder leafDry openareaKinesis increases the chance that a sow bug will encounter and stayin a moist environment.

27 TaxisA taxis is a more or less automatic, oriented movement toward or away from a stimulusMany stream fish exhibit positive rheotaxis; they automatically swim in an upstream directionThis taxis prevents them from being swept away and keeps them facing the direction from which food will come

33 Chemical CommunicationMany animals that communicate through odors emit chemical substances called pheromonesWhen a minnow or catfish is injured, an alarm substance in the fish’s skin disperses in the water, inducing a fright response among fish in the area

34 LE 51-9Minnows are widely dispersed in an aquarium before an alarm substance is introduced.Within seconds of the alarm substance being introduced, minnows aggregate near the bottom of the aquarium and reduce their movement.

35 Auditory CommunicationExperiments with insects have shown that courtship songs are under genetic control

37 Genetic Influences on Mating and Parental BehaviorA variety of mammalian behaviors are under relatively strong genetic controlResearch has revealed the genetic and neural basis for mating and parental behavior of male prairie voles

39 Concept 51.3: Environment, interacting with an animal’s genetic makeup, influences the development of behaviorsResearch has revealed that environmental conditions modify many of the same behaviors

40 Dietary Influence on Mate Choice BehaviorAn example of environmental influence is the role of diet in mate selection by Drosophila mojavensisExperiments have demonstrated that food eaten by larvae influences later mate choice in females

46 LearningLearning is modification of behavior based on specific experiencesLearned behaviors range from very simple to very complex

47 HabituationHabituation is a simple form of learning that involves loss of responsiveness to stimuli that convey little or no informationFor example, a hydra contracts when disturbed by a slight touch, but it stops responding if repeatedly disturbed without further consequences

48 Video: Bee PollinatingSpatial LearningSpatial learning is a more complex modification of behavior based on experience with the spatial structure of the environmentNiko Tinbergen showed how digger wasps use landmarks to find nest entrancesVideo: Bee Pollinating

50 Cognitive MapsA cognitive map is an internal representation of spatial relationships between objects in an animal’s surroundings

51 Associative LearningIn associative learning, animals associate one feature of their environment with anotherClassical conditioning is a type of associative learning in which an arbitrary stimulus is associated with a reward or punishment

55 Cognition and Problem SolvingCognition is the ability of an animal’s nervous system to perceive, store, process, and use information gathered by sensory receptorsProblem solving can be learned by observing behavior of other animalsVideo: Chimp Cracking Nut

67 Migratory Patterns in BlackcapsField and laboratory studies of blackcap birds provided evidence of a genetic basis for migratory orientationBirds placed in funnel cages left marks indicating the direction they were trying to migrate

68 LE 51-21aBlackcaps placed in a funnel cage left marks indicating the direction in which they were trying to migrate.

69 Migratory orientation of wintering adult birds captured in Britain was very similar to that of their laboratory-raised offspringOffspring of British blackcaps and young birds from Germany were raised under similar conditions but showed very different migratory orientations

70 LE 51-21b N Adults from Britain and F1 offspring of British adultsWESGERMANYNYoungfrom SWGermanyWESMediterraneanSeaWintering blackcaps captured in Britain and their laboratory-raised offspring had a migratory orientation toward the west, while young birds from Germany were oriented toward the southwest.

72 Foraging BehaviorOptimal foraging theory views foraging behavior as a compromise between benefits of nutrition and costs of obtaining food

73 Energy Costs and BenefitsReto Zach conducted a cost-benefit analysis of feeding behavior in crowsThe crows eat molluscs called whelks but must drop them from the air to crack the shellsOptimal flight height correlated with fewer drops, indicating a trade-off between energy gained (food) and energy expended

74 Average number of dropsLE 51-22125605010040Average number of dropsAverage number of drops3075Total flight height (number of drops drop height in m)Total flight height20Drop heightpreferredby crows = 5.23 m501025235715Height of drop (m)

79 Mating Behavior and Mate ChoiceMating behavior is the product of a form of natural selection call sexual selection

80 Mating Systems and Mate ChoiceThe mating relationship between males and females varies greatly from species to speciesIn many species, mating is promiscuous, with no strong pair-bonds or lasting relationships

82 LE 51-25aSince monogamous species, such as these trumpeter swans, are often monomorphic, males and females are difficult to distinguish using external characteristics only.

83 In polygyny, one male mates with many femalesThe males are often more showy and larger than the females

84 LE 51-25bAmong polygynous species, such as elk, the male (left) is often highly ornamented.

85 In polyandrous systems, one female mates with many malesThe females are often more showy than the males

86 LE 51-25cIn polyandrous species, such as these Wilson’s phalaropes, females (top) are generally more ornamented than males.

87 Needs of the young are an important factor constraining evolution of mating systemsCertainty of paternity influences parental care and mating behaviorCertainty of paternity is much higher when egg laying and mating occur together, as in external fertilizationIn species with external fertilization, parental care is at least as likely to be by males as by females

89 Sexual Selection and Mate ChoiceIn intersexual selection, members of one sex choose mates on the basis of certain traitsIntrasexual selection involves competition between members of one sex for mates

90 Mate Choice by FemalesMale zebra finches are more ornate than females, a trait that may affect mate choice by the females

92 Imprinting of female chicks on males with more ornamentation affects mate selection as adultsExperiments suggest that mate choice by female zebra finches has played a key role in evolution of ornamentation in male zebra finches

93 LE 51-28 Experimental Groups Control Group Both parents ornamentedMalesornamentedFemalesornamentedParents notornamentedResultsFemales reared by ornamented mothers or nonornamented parents showed no preference for either ornamented or nonornamented males.Females reared by ornamented parents or ornamented fathers preferred ornamented males as mates.Males reared by all experimental groups showed no preference for either ornamented or nonornamented female mates.

94 The size of eyestalks in stalk-eyed flies affects which males the females choose to mate withStudies of such behavior support the hypothesis that females base mate choices on characteristics that correlate with male quality

96 Male Competition for MatesMale competition for mates is a source of intrasexual selection that can reduce variation among malesSuch competition may involve agonistic behavior, an often ritualized contest that determines which competitor gains access to a resource

101 Applying Game TheoryGame theory evaluates alternative strategies where the outcome depends on each individual’s strategy and the strategy of other individualsMating success of male side-blotched lizards is influenced by male polymorphism and the abundance of different males in a given area

103 Concept 51.6: The concept of inclusive fitness can account for most altruistic social behaviorMany social behaviors are selfishNatural selection favors behavior that maximizes an individual’s survival and reproduction

104 AltruismOn occasion, some animals behave in ways that reduce their individual fitness but increase the fitness of othersThis kind of behavior is called altruism, or selflessnessIn naked mole rat populations, nonreproductive individuals may sacrifice their lives protecting the reproductive individuals from predators

106 Inclusive Fitness Altruism can be explained by inclusive fitnessInclusive fitness is the total effect an individual has on proliferating its genes by producing offspring and helping close relatives produce offspring

107 Hamilton’s Rule and Kin SelectionHamilton proposed a quantitative measure for predicting when natural selection would favor altruistic acts among related individualsThree key variables in an altruistic act:Benefit to the recipientCost to the altruistCoefficient of relatedness (the probability that if two individuals share a parent or ancestor, a gene in one individual will also be present in the second individual)

109 Natural selection favors altruism when the benefit to the recipient multiplied by the coefficient of relatedness exceeds the cost to the altruistThis inequality is called Hamilton’s ruleKin selection is the natural selection that favors this kind of altruistic behavior by enhancing reproductive success of relativesAn example of kin selection and altruism is the warning behavior in Belding’s ground squirrels

119 Evolution and Human CultureHuman culture is related to evolutionary theory in the distinct discipline of sociobiologyHuman behavior, like that of other species, results from interactions between genes and environmentHowever, our social and cultural institutions may provide the only feature in which there is no continuum between humans and other animals